/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Text;
using System.Xml;
using Spring.Util;

namespace Spring.Core.IO;

/// <summary>
/// Used when retrieving information from the standard .NET configuration
/// files (App.config / Web.config).
/// </summary>
/// <remarks>
/// <p>
/// If created with the name of a configuration section, then all methods
/// aside from the description return <see langword="null"/>,
/// <see langword="false"/>, or throw an exception. If created with an
/// <see cref="System.Xml.XmlElement"/>, then the
/// <see cref="Spring.Core.IO.ConfigSectionResource.InputStream"/> property
/// will return a corresponding <see cref="System.IO.Stream"/> to parse.
/// </p>
/// </remarks>
/// <author>Mark Pollack</author>
/// <author>Rick Evans</author>
public class ConfigSectionResource : AbstractResource
{
    private XmlElement configElement;
    private string sectionName;

    /// <summary>
    /// Creates new instance of the
    /// <see cref="Spring.Core.IO.ConfigSectionResource"/> class.
    /// </summary>
    /// <param name="configSection">
    /// The actual XML configuration section.
    /// </param>
    /// <exception cref="System.ArgumentNullException">
    /// If the supplied <paramref name="configSection"/> is <see langword="null"/>.
    /// </exception>
    public ConfigSectionResource(XmlElement configSection)
    {
        AssertUtils.ArgumentNotNull(configSection, "configSection");
        sectionName = configSection.Name;
        configElement = configSection;
    }

    /// <summary>
    /// Creates new instance of the
    /// <see cref="Spring.Core.IO.ConfigSectionResource"/> class.
    /// </summary>
    /// <param name="resourceName">
    /// The name of the configuration section.
    /// </param>
    /// <exception cref="System.ArgumentNullException">
    /// If the supplied <paramref name="resourceName"/> is
    /// <see langword="null"/> or contains only whitespace character(s).
    /// </exception>
    public ConfigSectionResource(string resourceName) : base(resourceName)
    {
        AssertUtils.ArgumentHasText(resourceName, "resourceName");
        sectionName = GetResourceNameWithoutProtocol(resourceName);
        configElement = (XmlElement) ConfigurationUtils.GetSection(sectionName);
    }

    /// <summary>
    /// Returns the <see cref="System.Uri"/> handle for this resource.
    /// </summary>
    /// <remarks>
    /// <p>
    /// This implementation always returns <see langword="null"/>.
    /// </p>
    /// </remarks>
    /// <value>
    /// <see langword="null"/>.
    /// </value>
    /// <seealso cref="Spring.Core.IO.IResource.Uri"/>
    public override Uri Uri
    {
        get { return null; }
    }

    /// <summary>
    /// Returns a <see cref="System.IO.FileInfo"/> handle for this resource.
    /// </summary>
    /// <remarks>
    /// <p>
    /// This implementation always returns <see langword="null"/>.
    /// </p>
    /// </remarks>
    /// <value>
    /// <see langword="null"/>.
    /// </value>
    /// <seealso cref="Spring.Core.IO.IResource.File"/>
    public override FileInfo File
    {
        get { return null; }
    }

    /// <summary>
    /// Returns a description for this resource (the name of the
    /// configuration section in this case).
    /// </summary>
    /// <value>
    /// A description for this resource.
    /// </value>
    /// <seealso cref="Spring.Core.IO.IResource.Description"/>
    public override string Description
    {
        get
        {
            return string.Format("config [{0}#{1}]", ConfigurationUtils.GetFileName(configElement), sectionName);
        }
    }

    /// <summary>
    /// Does this resource actually exist in physical form?
    /// </summary>
    /// <remarks>
    /// <p>
    /// This implementation always returns <see langword="false"/>.
    /// </p>
    /// </remarks>
    /// <value>
    /// <see langword="false"/>
    /// </value>
    /// <seealso cref="Spring.Core.IO.IResource.Exists"/>
    /// <seealso cref="Spring.Core.IO.IResource.File"/>
    public override bool Exists
    {
        get { return false; }
    }

    /// <summary>
    /// Return an <see cref="System.IO.Stream"/> for this resource.
    /// </summary>
    /// <value>
    /// An <see cref="System.IO.Stream"/>.
    /// </value>
    /// <exception cref="System.IO.IOException">
    /// If the stream could not be opened.
    /// </exception>
    /// <seealso cref="Spring.Core.IO.IInputStreamSource"/>
    public override Stream InputStream
    {
        get
        {
            if (configElement == null)
            {
                throw new FileNotFoundException(string.Format("Configuration Section '{0}' does not exist", this.sectionName), this.sectionName);
            }

            return new MemoryStream(Encoding.UTF8.GetBytes(configElement.OuterXml));
        }
    }

    /// <summary>
    /// Exposes the actual <see cref="System.Xml.XmlElement"/> for the
    /// configuration section.
    /// </summary>
    /// <remarks>
    /// <p>
    /// Introduced to accomodate line info tracking during parsing.
    /// </p>
    /// </remarks>
    internal XmlElement ConfigElement
    {
        get { return configElement; }
    }
}
